On October 16, 1846, Thomas WG Morton administered ether to the patient Gilbert Abbott, while Dr John Collins Warren cut a tumor from his neck. It was the first use of anesthesia in a surgical procedure and it happened in this domed operating room in Mass General Hospital. The dome is still used today for meetings and lectures, so it is sometimes closed to the public.
The dome looks like a typical, old-fashioned hall used for lectures and medical demonstrations, up to and including the skeleton hanging in the corner. There are a few other items to see, including a painting of the first anesthetized surgery.